Practical: To investigate whether heat is given off during respiration
MEMO
FOCUS QUESTION: Do seeds that are respiring (bean seeds that are respiring) give off more
heat than seeds that are dead and therefore not respiring?
RESULTS: Write in a suitable heading and fill in the table below:
A table showing the heat given off by germinating bean seeds (experiment) that are respiring
compared to bean seeds that are not respiring (control) over a period of 72 hours.
From the results it can be seen that the germinating bean seeds (experiment) gave off more
heat over 72 hours whereas the seeds that were not respiring (control) didn’t seem to give off
much or any heat at all.
CONCLUSION:
The hypothesis was supported in that the bean seeds that were germinating and therefore
respiring (experiment) gave off more heat than those seeds that were boiled and therefore not
respiring (control).
QUESTIONS:
1. It is considered to be a scientific investigation as one variable was manipulated/changed
which had an effect on the dependent variable. In this case the seeds were either
germinating or killed and the amount of heat generated from these seeds was measured.
A scientific procedure is when there are fixed steps that are carried out and no variables are
manipulated/changed.
(3)
2. Formalin kills any bacteria or fungi that might grow on the dead seeds.
(1)
3. Thermos flasks are good insulators and therefore limit the effect of the outside
environmental temperature on the readings given by the thermometer .
(2)
4. Cotton wool is used as it allows gases to pass in and out of the flask as the germinating
seeds will need oxygen and give off carbon dioxide during respiration/a rubber stopper
would not allow the gases that are necessary for respiration in and out of the flask.
(2)
1
5. The flasks were inverted because of the following reasons:
 It allows for carbon dioxide which is a heavy gas to move freely out of the bottom of the
flask.
 Hot air rises and so because the flask is inverted it is able to trap the heat.
 The thermometer can be easily read if the flask is inverted as it won’t have to be pushed
far down into the flasks.
(3)
6. The control test is the apparatus in which the independent variable is removed/taken
away this is done to compare the change/difference in results with the experimental
test/The control test is the apparatus with the dead bean seeds/the bean seeds that are
not respiring. 
(2)
7. As fungi and bacteria are living organisms they would respire. This would affect the
results as heat would be generated by them in the control apparatus and will therefore not be
due to the bean seeds respiring.
(2)
8. The bean seeds that are respiring/germinating and the bean seeds that have been boiled
(1)
9. The heat given off by the bean seeds.
(1)
10. The type of seeds that were used were all bean seeds
The volume/number of seeds in each flask was equal
The type of thermos flask used for each apparatus was the same
The time of day that the daily temperature reading was taken was the same
The time that each apparatus was set up was the same
The location where each apparatus was placed was the same
ANY THREE CORRECTLY STATED FIXED/CONTROLLED VARIABLES
(3)
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TOTAL 20 MARKS
2